Obstructive lung disease is divided in asthma (reversible) and chronic obstructive pulmonary disease (COPD [nonreversible]), but in clinical practice this distinction is often difficult to make—especially in older patients. In about 20% of patients, asthma and COPD may coexist. In the session titled “Asthma-COPD overlap syndrome: A new disease or old news?” at the 2015 American College of Chest Physicians meeting in Montreal, a group of experts clarified the clinical manifestations, ramifications, and treatment of this overlap syndrome.
Asthma-COPD overlap syndrome (ACOS), as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and Global Initiative for Asthma (GINA) consensus statement, is “Characterized by persistent airflow obstruction with several features usually associated with asthma and several features usually associated with COPD.”1 In clinical practice, if the number of features suggestive of asthma and COPD are equal in number, a diagnosis of ACOS should be considered. ACOS is a significant health problem; 27% of COPD patients have an overlap with asthma and 20% of older adults with asthma have an overlap with COPD. This overlap has important clinical ramifications, since these patients have worse pulmonary symptoms and quality of life with more frequent exacerbations than with either condition alone. There is a 2- to 6-fold greater utilization of health resources with ACOS than patients with either disease alone.
Knowledge of ACOS at the primary care level is essential; the GOLD guidelines note that the primary care physician may be the first to suspect or identify ACOS. A recent study2 among asthma patients seen in primary care found the prevalence of ACOS to be 27.4%. These patients had no previous diagnosis of COPD, but were either current or ex-smokers with a smoking history of at least 10 pack-years. The patients with ACOS were older and had smoked more than patients with asthma alone.
The distinction between asthma, COPD, and ACOS is often a difficult one to make. Bronchodilator (BD) responsiveness, which is classically reported in early asthma, is also seen in about 60% of COPD patients. Irreversible airway obstruction, which is classically reported in COPD patients, is often seen in patients with long-standing asthma. Sputum eosinophil count and exhaled nitric oxide are also often elevated in COPD and do not help in distinguishing among the three entities. Patients with ACOS are usually older with a significant smoking history. Spirometry may show incomplete reversibility of obstruction with positive BD response. ACOS patients have been found to have less emphysema, greater airway wall thickness, and more gas trapping than COPD patients. Epidemiologic data, biomarkers, genetic and genomic studies suggest that ACOS shares inflammatory markers with asthma.
Treatment guidelines provide scant advice on how these patients should be managed. ACOS patients have been specifically excluded from clinical trials of asthma and COPD treatments. No double blind, prospective trials have been done with ACOS patients. Treatment guidelines for COPD and asthma as recommended by GOLD and GINA respectively can be followed. Dr. Stephen Bernard from University of Nebraska concluded, “If you got it, treat it and if you got both, treat both.”
Panel presentation. The asthma-COPD overlap syndrome: A new disease or old news? Presentation at 2015 American College of Chest Physicians Conference – CHEST 2015; October 25, 2015; Montreal, Canada.
Postma DS, Rabe KF. The asthma-COPD overlap syndrome. N Engl J Med. 2015;373:1241-1249. doi: 10.1056/NEJMra1411863. Review. PubMed PMID: 26398072. http://www.nejm.org/doi/full/10.1056/NEJMra1411863
Kiljander T, HelinT, Venho K, et al. Prevalence of asthma–COPD overlap syndrome among primary care asthmatics with a smoking history: a cross-sectional study. npj Primary Care Resp Med. (2015) 25, 15047; doi:10.1038/npjpcrm.2015.47; published online 16 July 2015 http://www.nature.com/articles/npjpcrm201547
GINA-GOLD consensus document: Diagnosis Of Diseases Of Chronic Airflow Limitation: Asthma, COPD and Asthma–COPD Overlap Syndrome.
GINA reports: http://www.ginasthma.org
GOLD reports: http://www.goldcopd.org